Tractors are used in North America for row crop farming. Such a tractor should be able to have wheel tread spacings to accommodate crops grown in 30 inch row spacings, such as corn and soybeans. Larger and more powerful tractors require larger tire sizes to support the increased weight and to prevent soil compaction. As front tires increase in diameter on the steerable front axle, the maximum tractor turn angle decreases because the tire will contact the chassis of the tractor when adjusted to a 60 inch tread setting. In such cases, the maximum turn angle can be increased by moving the tires outwardly and away the tractor chassis. But, this results in a larger wheel spacing, and such a larger wheel spacing may make the tractor too wide for transporting along a road or highway. Thus, it is desired to provide a mechanism which can temporarily increase the maximum turn angle by increasing wheel spacing, such as during a turn.